BRZ Rally Car

In reply to ¯\_(ツ)_/¯ :

That is REALLY CHEAP for a rally spec cage, from someone who knows what he is doing (meaning, you won't have to go back two or three times when getting a logbook)

Also.... MUDFLAP!

If he comes up to New England for the Maine Forest Rally, I'd possibly have work for him.

Pete. (l33t FS) said:

In reply to ¯\_(ツ)_/¯ :

That is REALLY CHEAP for a rally spec cage, from someone who knows what he is doing (meaning, you won't have to go back two or three times when getting a logbook)

 

Also.... MUDFLAP!

Cool to see GRMers working with Adam!  

The Volvo and the BRZ have changed places:

In reply to eastsideTim :

Adam SHOULD be on GRM.

Pete. (l33t FS) said:

In reply to eastsideTim :

Adam SHOULD be on GRM.

I think he is too busy living life for that.

Cant wait to see the results on the BRZ cage.

Pete. (l33t FS) said:

I think I see the plan.  Adam will make the 240's cage, then he'll use the offcuts to make the BRZ cage

Just for you:

So far so AWESOME- it's pretty hard to make straight tubes and bends fit such a round car any better than this:

Looking GOOD!

At some point I'm going to do a "here are the choices we made and the wizardry Adam performed to arrive at this cage" but for now I'm happy just posting progress pictures:

Nice looking cage, of course.  You should probably climb into that back seat area and say goodbye, since you'll never be in there again lol....

Just out of curiosity, how many spare tires are you going to be able to carry, 1 or 2? 

In reply to eastsideTim :

Can carry two if I want!  See here:

This is also why the rear crossbar ended up where it did.

In reply to ¯\_(ツ)_/¯ :

Excellent.  Looks like good planning!

Please do post about the thought process and trade offs.  I'd be very interested to see that.

Also the "eventually" in this thread title is total BS.

Where does the door bar gusset start?  Where does it end?

We've got mobius gussets over here.

In reply to TVR Scott (Forum Supporter) :

I'll get there, I want to be far enough along to get pictures of absolutely all of it though.  Maybe tomorrow.

In reply to ¯\_(ツ)_/¯ :

Mobius Gusset should be your next band name. 

Some extreme connect the dots is happening:

I hear Adam had to bring an extra six feet of tubing just to reach those tall ass  front strut towers ;)

OK, so, obviously the rules (FIA 253 appendix J) spell out what the cage needs, but there were still some choices to be made on the way through so I'm going to try and highlight those.  Any questions please feel free to ask as quickly as possible, since I'm writing this as Adam puts the finishing touches on things so I can still go over stuff with him.

Working from back to front, we've got the rear cage foot- that is basically a triangle piece that ties the rear towers into the shell even more.  We technically could have just used the rear towers as the foot but more reinforcement doesn't hurt and Adam's welds are much better than mine.

Then, there's the node where the backstays and diagonals and crossbar all meet.  You've already seen that the crossbar just barely clears the spare tire, but the other important thing here is that there are lower diagonals completing the triangle which wouldn't clear the floor/wheel well if the point was lower.

Moving toward the front, you can see that lower diagonal barely clearing the wheel well.  The feet for the main hoop land on the "shelf" where the rear seat used to be, on top of a pretty chunky portion of the unibody which is actually outside the perimeter of the gas tank.  The feet are juuuuuust barely tall enough to allow clearance to shift the main portion of the cage down to weld all the top bits early in the process.

The fore/aft location of the main hoop is a little hard to see relative to the roof, but it basically tucks up in between two stock roof support pieces getting us a little extra clearance.  You can also see how the "V" in the roof bars still clears thanks to the curvature of the roof.  The roof bars have a bend in them further forward also, getting a little extra helmet clearance.

Next photo has a lot going on- the temple bar seen in top right is basically as big as it can be without hitting either the seat or the window.  The door bars are both continuous (rather than splitting one tube to make an X) so that they can't potentially break in the middle and turn into a javelin in a really big side impact.   The bend is pushed forward a bit so that it's easier to get in and out of the car, and the height at the rear is a little below the shoulder line.  The sill bar is as low as possible, and while it's arguably not totally necessary to have one I wanted a little more protection if we slide off the road into a low solid thing like a big stump or a rock.

The A pillar bars end before the stock dash bar- we're keeping that rather than making a new one that ties into the cage, primarily because the electric power steering stuff on this car all lives on the column and mounts to the stock dash bar so we figured it was best to leave it alone.

The seat mounts are tied into the shell, and are basically big threaded bungs welded into some tubes with plates to spread the load at the ends.  Keeping the seat mounts off the floor makes it less likely that a big rock hit from underneath will move them, and some bracket removal and hammering helped them get as low as reasonably possible.  The stock front seat mount (rectangle thing) was retained as an additional piece to keep the floor from coming up if we end up on some jagged rocks at some point.

The front cage feet are as far outwards as reasonably possible, so that there isn't a huge sharp cornered box in the footwell trying to break your leg.  It's not visible in this photo, but it also straddles a seam in the unibody that ties the inner rocker to the stamping that makes up the inner fender area.

The front tower supports are difficult to photograph since they go through so much stuff, but basically they pass through the firewall next to the stock wiring and tie the towers to the A pillar portion of the cage on both sides.  I asked Adam to do this bent plate to further reinforce the front towers since, again, I trust his welding more than my own.  If I have him do another one of these I'll just tack the towers in place and let him do the rest.

That's more or less all of it, the magic is in how tightly everything fits to the chassis and how the tubes come together in nice nodes and form complete triangles almost everywhere.  It should be super strong, hopefully I never have to test it but, you know, rally.

Did you just sit in the garage and watch him work for a week? I don't think I would have gone back in the house. 

In reply to mazdeuce - Seth :

I was back and forth a lot, but sometimes I had to force myself to stay out of the way and not interrupt the magic as it happened.  

That's really artwork.